PROGRESS IN EXPERIMENTAL PSYCHOLOGY 



furnished the point of departure for studies that led to 

 a better understanding of the modus operand! of the 

 mind's activities than had ever previously been attained 

 bv the most subtle of psychologists. 



m 



The \vork of the nerve physiologists had thus an im- 

 portant bearing on questions of the mind. But there 

 was another company of workers of this period who 

 made an even more direct assault upon the " citadel of 

 thought." A remarkable school of workers had devel- 

 oped in Germany, the leaders being men who, having 

 more or less of innate metaphysical bias as a national 

 birthright, had also the instincts of the empirical scien- 

 tist, and whose educational equipment included a pro- 

 found knowledge not alone of physiology and psycholo- 

 gy, but of physics and mathematics as well. These men 

 undertook the novel task of interrogating the relations 

 of body and mind from the stand-point of physics. 

 They sought to apply the vernier and the balance, as far 

 as might be, to the intangible processes of mind. 



The movement had its precursory stages in the early 

 part of the century, notably in the mathematical psy- 

 chology of Herbart, but its first definitiveoutputtoattract 

 general attention came from the master-hand of Hermann 

 Helmholtz in 1851. It consisted of the accurate measure- 

 ment of the speed of transit of a nervous impulse along 

 a nerve tract. To make such measurement had been re- 

 garded as impossible, it being supposed that the flight of 

 the nervous impulse was practically instantaneous. But 

 Helmholtz readily demonstrated the contrar} r , showing 

 that the nerve cord is a relatively sluggish message- 



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